Mercury, the closest planet to the sun, is named after the fleet-footed messenger of the gods. Venus is named after the goddess of love and beauty, whereas Mars is named after the god of war. Jupiter, the largest planet, is named after the king of the Roman gods. Saturn is named after the god of agriculture. Neptune is named after the god of the sea, and Pluto is named after the god of the underworld.

Uranus is different, as it was named after the Greek sky-god Ouranos. Earth's name has Germanic and Old English roots.

Mercury, Venus, Earth and Mars are small, rocky planets. They are separated from the other planets by the asteroid belt. Jupiter, Saturn, Uranus and Neptune are giant planets that do not have solid surfaces but rather are made of hydrogen and helium gas. Uranus and Neptune also have ammonia and methane ices in their atmospheres. All are thought to have solid cores, and all of them have rings and moons.